you’re computer might be compromised. Given the first tab in your browser I’m assuming you’re holding your private key (wallet) on your PC. Be wary of any other wallets on your PC. I recommend sending your funds from wallets on your PC to another wallet, preferably a hardware wallet. If you’ve got no other option, make a wallet on your phone and send it to that one.

Did you put out your private key anywhere in the internet? Like someone scamming you saying, “put in private key here for Callisto or more ETC.” If you put your private key anywhere in the internet, someone is going to take it.

This is an unfortunate situation with limited information. Afaik with the info provided your machine may most likely be compromised which is why transactions are being created and used to withdraw ETC from your wallet.
One way or another it’s compromised and unfortunately not much can be done by us, and nothing can be done by ETC, as the protocol is working as it should here.

You can take steps to mitigate your losses by creating a new wallet and sending the remainder of your funds but maybe by now its too late.

My guess is it was phishing site but it could be a number of things. Truly sorry for your issue